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使用正电子湮没寿命光谱法测定沸石咪唑酯骨架的孔隙率
Microporous and Mesoporous Materials
(
IF
4.8
)
Pub Date : 2022-12-01
, DOI:
10.1016/j.micromeso.2022.112389
J. Mor
,
P. Utpalla
,
J. Bahadur
,
D. Sen
,
S.K. Sharma
沸石咪唑酯骨架 (ZIF) 由于其结晶形态而具有精心设计的孔结构。由于其高表面积、孔体积和明确的孔网络,ZIF 在气体分离、气体储存、催化和传感器方面显示出巨大的应用潜力。为了将 ZIF 用于上述应用,研究粉末或薄膜形式的 ZIF 的孔结构(孔径、孔径分布和互连性)是非常必要的。由于超微孔隙率和压力依赖性框架的灵活性,发现传统的气体吸附技术无法提供 ZIF 的完整孔结构。近年来,正电子湮没寿命谱 (PALS) 已被用于研究少数 ZIF 的孔隙率。0.52 -8、Zn 0.25 Co 0.75 -ZIF-8、ZIF-8A)已经进行。这些框架是在室温下或使用溶剂热法合成的。这些 ZIF 的 PALS 测量证实了这些框架中存在不同类型的互连孔隙。将估计的孔径与通过其他常规技术确定的孔径进行比较。本研究表明,PALS 是一种强大的技术,可用于研究调整所有类型 ZIF 的孔隙结构。确定的孔径是不含人工制品的去溶剂化散装 ZIF 样品的实际平均孔径。这些孔径可能与 ZIF 的孔径依赖性分离性能相关。
"点击查看英文标题和摘要"
Porosimetry of zeolitic imidazolate frameworks using positron annihilation lifetime spectroscopy
Zeolitic Imidazolate Frameworks (ZIFs) owing to their crystalline morphology have well designed pore architecture. ZIFs show great potential for applications in gas separation, gas storage, catalysis and sensors because of their high surface area, pore volume and well defined pore network. In order to utilize ZIFs for aforementioned applications, investigation of pore architecture (pore size, pore size distribution and interconnectivity) of ZIFs in powder or film form is highly essential. Conventional gas adsorption techniques are found to be incapable for providing complete pore architecture of ZIFs due to ultra-microporosity and pressure dependent framework flexibility. In recent years, positron annihilation lifetime spectroscopy (PALS) has been used to investigate the porosity of few ZIFs. In order to establish the applicability of PALS for pore architecture investigation of ZIFs in general, a systematic study for a number of ZIFs (ZIF-67, ZIF-8, ZIF-7l, ZIF-7n ZIF-62, ZIF-90, ZIF-70.52-8, Zn0.25Co0.75-ZIF-8, and ZIF-8A) have been carried out. These frameworks have been synthesized at room temperature or using solvothermal methods. PALS measurements of these ZIFs confirm the presence of different types of interconnected pores in these frameworks. The estimated pore sizes are compared with the pore sizes determined from other conventional techniques. The present study suggests that PALS is a powerful technique for the investigation of tuning of the pore architecture of all type of ZIFs. The determined pore sizes are the factual average pore size of desolvated bulk ZIF samples free from artifacts. These pore sizes could be correlated with the pore size dependent separation performance of ZIFs.
更新日期:2022-12-06